This invention relates to engine fluid compartment covers and ignition systems for spark ignition internal combustion engines.
Spark ignition internal combustion engines such as are used in automobiles have traditionally employed mechanical or electronic distributors to route high voltage spark energy from an ignition coil to the engine spark plugs. More recently, distributorless ignition systems have been employed in which a separate ignition coil is provided for every one or two spark plugs. In some instances, the coils are installed directly above or into the spark plug. In other instances they are integrated together into a common housing or assembly for installation above the spark plugs as a single unit, and this integrated approach has been proposed for both distributor-based and distributorless systems.
For example, U.S. Pat. No. 4,669,443 to Oetting et al. discloses an integrated ignition system in which a cylinder head cover mates with the engine to define a first enclosed cover space for the valve assembly overhead cam and a second enclosed space for the spark plugs. The cover can include a distributor and ignition coil with leads that route the high voltage to annular contact rings electrically connected to the spark plugs. U.S. Pat. No. 5,743,235 to Lueder discloses an air intake manifold having a distributor and molded-in high voltage wires that lead to external lugs where they are then connected to each spark plug via spark plug wires.
In distributorless systems, a number of different approaches have been proposed for incorporating the ignition coils into a common assembly. For example, U.S. Pat. No. 5,771,850 to Okada discloses different embodiments of a cylinder head cover that includes for each spark plug an ignition coil mounted either under the cover or in an exposed location on the top of the cover. The cover includes either a printed circuit or embedded conductors that provide power to the coil primary from a connector on the cover. Although this design involves a fairly direct connection of the coil""s high voltage secondary to the spark plugs, it is also known in distributorless systems to route the high voltage from the coil to the spark plugs using molded-in high voltage conductors. This is shown in U.S. Pat. No. 4,706,639 to Boyer et al. In that patent, the ignition module includes a plastic housing that includes the ignition coils in a central location with conductors embedded in a lower wall of the housing to carry the high voltage from the coils to terminals located on the bottom side of the lower wall. The terminals are electrically connected to the spark plugs via a spring or conductive material. The housing includes a metal cover which partially extends over a pair of separate dual-overhead cam covers.
Various other approaches to an integrated ignition system have been proposed. U.S. Pat. No. 4,903,675 to Huntzinger et al. discloses an integrated ignition system which includes a primary winding module that comprises a horizontal support portion and a plurality of downwardly-extending spaced tubular extensions, each of which has a primary winding coil open at its lower end so that it can fit directly onto its associated spark plug. Each spark plug includes a high voltage secondary so that when the primary winding module is installed with each of the tubular extensions fitted over its associated spark plug, the primary windings in the tubular extensions surround and magnetically couple to the secondary windings in the spark plug to thereby transfer spark energy to the secondaries. See also, U.S. Pat. No. 5,109,828 to Tagami et al.; U.S. Pat. No. 5,152,274 to Maekawa; U.S. Pat. No. 5,218,936 to Pritz et al.; and U.S. Pat. No. 5,390,648 to Yanase.
Although these prior art systems provide integration of various portions of the ignition system, they typically provide only limited integration or otherwise involve a tradeoff of modularity and ease of servicing for increased integration. For example, in the Boyer et al. patent, the housing and cover of the ignition module is separate from the cam covers. In the Oetting et al. patent, the distributor and ignition coil appear as an integral part of the cylinder head and apparently not separately replaceable. The Okada cylinder head cover involves locating the ignition coils either under the cover, where they are not easily accessible, or on top of the cover, where they are completely exposed and not protected. In either case, the coils are located directly above their associated spark plug and no provision is made for allowing them to be located in a laterally-spaced position on the cylinder cover.
The present invention is directed to an engine cover such as can be used for sealing engine oil or some other engine fluid within a compartment on a spark ignition internal combustion engine. The cover can be, for example, a rocker cover or, more generally, an overhead valve assembly cover. In accordance with one aspect of the invention, the cover comprises an engine fluid compartment cover that includes a housing, a first group of high voltage terminals, a second group of high voltage terminals, and a plurality of high voltage leads electrically connecting each terminal from the first group with at least one of the terminals from the second group to thereby permit high voltage spark energy to be transmitted through said housing. The housing has an upper wall and at least one side wall extending down from the upper wall to a mounting surface of the housing. The mounting surface has a conformation that mates with an associated surface of an engine fluid compartment on the engine such that, when the housing is mounted to the engine with the mounting surface in contact with its associated surface on the engine fluid compartment, the upper and side walls together enclose the engine fluid within an interior region below the upper wall. The first group of terminals are located at the outer surface of the upper wall and the second group of terminals are located at the inner surface of the wall. In this way, ignition coils or other ignition system components can be located on the outside of the cover in contact with the first group of terminals and the high voltage spark energy can then be routed through the housing by the high voltage leads to the second group of terminals that can be electrically connected to the individual spark plugs.
In accordance with another aspect of the invention, the cover can include a housing as described above, but with a separate compartment located above the upper wall to provide a protective enclosure for the ignition coils and/or other components. The first group of terminals can then each be located within the compartment, and a removable cover can be provided over the compartment. This serves the dual purpose of maintaining the high voltage portion of the ignition system within and underneath the housing while providing easy access to the ignition coils for servicing.